The subject matter disclosed herein relates to appliances using a mechanical refrigeration cycle, and more particularly to heat pump dryers and the like.
Clothes dryers have typically used electric resistance heaters or gas burners to warm air to be used for drying clothes. These dryers typically work on an open cycle, wherein the air that has passed through the drum and absorbed moisture from the clothes is exhausted to ambient. More recently, there has been interest in heat pump dryers operating on a closed cycle, wherein the air that has passed through the drum and absorbed moisture from the clothes is dried, re-heated, and re-used.
Commercial dryers include perforations and are equipped with a so-called “double tub,” wherein if dripping wet laundry is placed into a commercial dryer, the water goes through the perforations, collects and is drained away in the outer drum. This is advantageous because airflow can be introduced from the top and out the bottom, or in on the sleeve and out on the perimeter, or in the center and out the perimeter, at very high airflow rates, because there is almost no pressure drop. However, the double-tub construction is quite expensive.
For residential dryers, existing approaches for increases in grill area have had only marginal improvements in airflow at the expense of consumer access to the drum.